Frank Kogan

At least according to Wikipedia, the caption on the YouTube video is correct; the live performance of "Prisoner Of Love" is from Live At The Apollo, Volume II, which was released in 1968 but was recorded in 1967; I'd originally surmised the performance was shortly after the death of Little Willie John in May 1968, since in the call-and-response section James interpolates lyrics from several Little Willie John songs, presumably as a tribute ("Talk To Me, Talk To Me" "Let Them Talk," "Fever"). John had been imprisoned for manslaughter in July 1966, which might have been what inspired the tribute. Or maybe James just felt like doing a tribute.